The present invention relates generally to sandblasting apparatus, and more particularly to hand-portable sandblasting apparatus for treating surfaces of various configurations including concave, convex, and angular surfaces.
Hand-portable sandblasting devices for this purpose have been known generally, for example, from the Mead et al. U.S. Pat. No. 2,494,773 and the Bishop et al. U.S. Pat. No. 2,483,176.
In both of these above mentioned patents, the interior of the portable casing is a relatively large sandblasting chamber with a forward opening through which a nozzle discharges grit particles against a worksurface that is to be processed. The means to contact the worksurface comprises a circular brush means surrounding the opening of the casing to space the rim of the casing from the worksurface. A suction pump connected to the casing maintains a sufficient vacuum therein to withdraw the spent grit particles from the casing and causes sufficient inflow of air through the surrounding brush means to keep the grit particles from escaping into the atmosphere. The suction pump must operate at exceedingly high capacity in order for the device to function properly, and the required excessive volume of air inflow through the surrounding brush results in the placing of an unduly heavy load on the suction pump.